The crf 230f would be the perfect size for you. Its very reliable, durable, and low maintanence. Perfect bike for the trails especially for a begginer. The next step up would be a crf 250x and below the crf230f would be the crf150f.
I am 5'10 and iv been riding the crf230 for 2 years now. Im at the point where i want more power. If you have been riding for a few years then go with the crf 250x because the crf230 is a begginers/amatuer bike and it doesnt have insane power. But when on the trails i never need insane power so the 230 is awesome on the trails and for the slow tricky stuff.
Good luck!